The p115-interactive proteins GM130 and giantin participate in endoplasmic reticulum-Golgi traffic

ALVAREZ, C; GARCIA MATA, R; HAURI, HP; SZTUL, E

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda, Maryland; Año: 2001 vol. 276 p. 2693 - 2700

0021-9258

The transport factor p115 is essential for endoplasmicreticulum (ER) to Golgi traffic. P115 interacts with twoGolgi proteins, GM130 and giantin, suggesting that theymight also participate in ER-Golgi traffic. Here, we showthat peptides containing the GM130 or the giantin p115binding domain and anti-GM130 and anti-giantin antibodiesinhibit transport of vesicular stomatitis virus(VSV)-G protein to a mannosidase II-containing Golgicompartment. To determine whether p115, GM130, andgiantin act together or sequentially during transport,we compared kinetics of traffic inhibition. Anti-p115,anti-GM130, and anti-giantin antibodies inhibited transportat temporally distinct steps, with the p115-requiringstep before the GM130-requiring stage, and bothpreceding the giantin-requiring stage. Examination ofthe distribution of the arrested VSV-G protein showedthat anti-p115 antibodies inhibited transport at the levelof vesicular-tubular clusters, whereas anti-GM130 andanti-giantin antibodies inhibited after the VSV-G proteinmoved to the Golgi complex. Our results provide thefirst evidence that GM130 and giantin are required forthe delivery of a cargo protein to the mannosidase IIcontainingGolgi compartment. These data are mostconsistent with a model where transport from the ER tothe cis/medial-Golgi compartments requires the actionof p115, GM130, and giantin in a sequential rather thancoordinate mechanism.